The KENTRACK program is a finite element based railway trackbed structural design program that can be utilized to analyze trackbeds having various combinations of all-granular and asphalt-bound layered support. It is applicable for calculating compressive stresses at the top of subgrade, indicative of potential long-term trackbed settlement failure. Furthermore, for trackbeds containing asphalt layer, it is applicable for calculating tensile strains at the bottom of the asphalt layer, indicative of potential fatigue cracking. The program was recently expanded to include both English and international units. A procedure has been incorporated to provide a path to save results in a text formation in post-Windows XP operating systems. More importantly, properties of performance graded (PG) asphalt binders and the Witczak E* predictive model have been incorporated in the 4.0 Version of the program. Component layers of typical trackbed support systems are analyzed while predicting the significance of layer thicknesses and material properties on design and performance. The effect of various material parameters and loading magnitudes on trackbed design and evaluation, as determined and predicted by the computer program, are presented. Variances in subgrade modulus and axle loads and the incorporation of a layer of asphalt within the track structure have significant effects on subgrade vertical compressive stresses and predicted trackbed service lives. The parameter assessments are presented and evaluated using sensitivity analysis. Recommendations for future research are suggested.

Thesis (M.S.)--University of Nevada, Reno, 2008. / "May, 2008." Includes bibliographical references (leaves 155-160). Online version available on the World Wide Web.

Thesis (M.S.)--Brigham Young University. Dept. of Civil and Environmental Engineering, 2006. / Includes bibliographical references (p. 43-46).

Os objetivos deste trabalho são avaliar o comportamento de asfaltos peruanos convencional CAP PEN 60/70 e modificados por polímero SBS tipo I 60/60 e PG 76-22, em misturas asfálticas densas, sem e com envelhecimento em curto prazo, e estabelecer a distribuição do grau de desempenho (PG) de ligantes asfálticos com base nas condições climáticas de cada região do Peru. Para a classificação por desempenho os ligantes asfálticos procedentes de Peru foram submetidos aos ensaios convencionais e da especificação Superpave: penetração, ponto de amolecimento, viscosidade Brookfield, ponto de fulgor, retorno elástico, estabilidade a estocagem, envelhecimento em curto prazo (RTFOT), envelhecimento em longo prazo (PAV), cisalhamento dinâmico (DSR) e rigidez à fluência na flexão (BBR). Para a avaliação das propriedades mecânicas, sem envelhecimento e com envelhecimento em curto prazo, foram moldados um total de 196 corpos de prova, submetidos aos ensaios Marshall, resistência à tração, resistência à tração após umidade induzida, módulo de resiliência, fluência por compressão uniaxial estática, fluência por compressão uniaxial dinâmica e vida de fadiga. Os resultados dos ensaios mostram que o proceso de modificação dos asfaltos por polímero melhora as caracteristicas reológicas do ligante, apresentando menor índice de susceptibilidade térmica e maior resistência ao envelhecimento e melhorando o comportamento das misturas asfálticas em todos os ensaios mecânicos. Esses resultados foram confirmados pela análise estrutural com o programa computacional Elsym5, nas duas condições de envelhecimento estudadas. / The main goal of this work is the evaluation of the behavior of conventional peruvian asphalt binder AC PEN 60/70 and SBS polymer-modified asphalts I 60/60 and PG 76-22, when used in hot-mix asphalt (HMA), under both conditions with and without short-term aging. It aims also to establish the asphalt binder performance grade (PG), which is based on the weather conditions, for different peruvian regions. The peruvian asphalt binders were submitted to conventional and Superpave laboratory tests: penetration, softening point, Brookfield viscosity, flash point, elastic recovery, storage stability, rolling thin film oven test (RTFOT), pressure aging vessel (PAV), dynamic shear rheometer (DSR) and bending beam rheometer (BBR). For the evaluation of mechanical properties 196 specimen were sumitted to Marshall, indirect tensile strength under static loading, indirect tensile strength under static loading after induced moisture, resilient modulus under dynamic diametric compression, static and dynamic creep and fatigue tests. The result show that polymer-modified asphalt binder improve rheological characteristic, in terms of thermal susceptibility and resistance to aging, and also improve the asphalt mixtures behavior, which was verified in all of the mechanical tests and after the structural analysis performed with the Elsym5 program, for all of the short-term aging conditions studied in this work.

Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The UNFCCC (United Nations Framework Convention on Climate Change), enabled by the Kyoto Protocol, set enforced responsibilities on industrialised countries to reduce the amount of emissions (greenhouse gases) produced. This global call for the reduction of greenhouse gas emissions ensured that the manufacturing sector commit to emission reduction. The asphalt industry has embarked on a quest to find alternative methods of producing and constructing asphalt mixes which will release less greenhouse gasses into the atmosphere. These new methods include the reduction in production and construction temperatures which in turn will reduce the amount of greenhouse emissions produced. These new methods introduced the concept of warm mix asphalt (WMA) to the alternative hot mix asphalt (HMA). To produce a WMA mix at lower temperatures the binder needs to be in a workable state so to effectively coat the aggregate and produce a good quality mix. WMA technologies have been developed to enable production of mixes at lower temperatures (effectively reducing emissions) whilst retaining the required binder viscosity and properties needed to produce a quality mix. The question which needs to be answered is whether the performance of these WMA mixes can compare with that of HMA mixes. In this study several WMA mixes (with different WMA technologies) are evaluated against their equivalent HMA mixes in terms of fatigue life and flexural stiffness. Phase angle results were also considered. Flexural stiffness is a mix property which is dependent on loading time and temperature. It is used to measure the load spread ability of a mix and also influences fatigue behaviour. Fatigue cracking occurs in the material as a result of repeated cyclic loading. The evaluation and analysis conducted in this study show that WMA mixes can compare favourably and even exceed that of HMA mixes in certain cases, although some WMA mixes resulted in lower fatigue life or flexural stiffness than its corresponding HMA mixes, which could be attributed to differences in mix components and variables. In this study a literature study, methodology, laboratory test results, a comparison of mix results and conclusions and recommendations are made. / AFRIKAANSE OPSOMMING: Die UNFCCC (United Nations Framework Convention on Climate Change) was in staat gestel deur die Kyoto Protocol om verantwoordelikhede op geïndustrialiseerde lande te forseer om die hoeveelheid van nadelige kweekhuisgasse wat geproduseer word te verminder. Hierdie globale oproep tot die vermindering van kweekhuisgasse verseker dat die vervaardigingsektor hulself verbind tot emissie vermindering. Die asfalt industrie het begin met 'n soektog na alternatiewe metodes van vervaardiging en die bou van asfaltmengsels wat minder kweekhuisgasse sal vrystel in die atmosfeer. Hierdie nuwe metodes sluit die vermindering in produksie en konstruksie temperature in wat op sy beurt die hoeveelheid kweekhuisgasse geproduseer verminder. Hierdie nuwe metodes het die konsep van warm mengsel asfalt (WMA) bekendgestel teenoor die alternatiewe ‘hot’ mengsel asfalt (HMA). Om ‘n WMA mengsel te produseer by laer temperature, moet die bindmiddel in 'n werkbare toestand wees om die aggregaat heeltemal te bedek en 'n goeie gehalte mengsel te produseer. WMA tegnologie is ontwikkel om die produksie van mengsels teen laer temperature te realiseer (vermindering die uitlaatgasse), terwyl die vereiste bindmiddel viskositeit en eienskappe wat nodig is om 'n kwaliteit mengsel te produseer behou word. Die vraag wat beantwoord moet word, is of die prestasie van hierdie WMA mengsel kan vergelyk word met dié van HMA mengsel. In hierdie studie is 'n paar WMA mengsels (met verskillende WMA tegnologie) geëvalueer teen hul ekwivalent HMA mengsels in terme van vermoeiing en buig styfheid. Fase hoek resultate is ook in ag geneem. Buig styfheid is 'n mengsel eienskap wat afhanklik is van die laai tyd en temperatuur. Dit word gebruik om die las verspreiding vermoë van 'n mengsel te meet en beïnvloed ook vermoeiing gedrag. Vermoeidheid krake kom voor in die materiaal as gevolg van herhaalde sikliese laai. Die evaluering en ontleding in hierdie studie toon dat WMA mengsels goed vergelyk en selfs in sekere gevalle meer as dié van HMA mengsels, hoewel sommige WMA mengsels laer vermoeidheid lewe of buig styfheid as die ooreenstemmende HMA mengsels gewys het, wat toegeskryf kan word tot verskille in mengsel komponente en veranderlikes. In hierdie studie word 'n literatuurstudie, metodiek, laboratorium toets resultate, 'n vergelyking van die mengsel resultate en gevolgtrekkings en aanbevelings gemaak.

Este trabalho apresenta alguns resultados de pesquisa laboratorial compreendendo projeto de dosagem, comportamento mecânico da mistura SMA (Stone Matrix Asphalt - Matriz Pétrea Asfáltica), bem como, aspectos executivos relacionados ao desenvolvimento de um trecho experimental em SMA para revestimento de pavimentos. Os resultados de laboratório obtidos mostram que o SMA é um revestimento asfáltico que pode apresentar bom desempenho sob cargas pesadas em climas quentes, pois estas misturas são muito resistentes à deformação permanente, mas preservam a flexibilidade como os concretos asfálticos densos. O SMA é uma solução bem conhecida para tráfego pesado na Europa e mais recentemente na América do Norte. O SMA também tem sido empregado para aumento de aderência em pista molhada e para redução de ruído. / This research presents laboratory test results of mixture design, mechanical behavior of SMA (Stone Matrix Asphalt), as well as some construction aspects regarding to development of Brazilian road trial section as a new bituminous surface course to pavement construction or maintenance.The laboratory results show that SMA can perform very well in hot climate under heavy load conditions due to the mixture to be very resistant against permanent deformation but still flexible like dense asphalt concrete. The SMA is a well Known solution for heavy traffic in Europe and, more recently, in North America. The SMA is also employed to increase the adherence in wet conditions and for noise reduction.

The Superpave mix design system is being adopted by most of the states in the Unites States. Since the Superpave system was developed on the basis of data mostly obtained from medium to high traffic volume roads, there is a need to develop criteria for mix design for Hot Mix Asphalt (HMA) mixes for low traffic volume roads. In this study funded by the six New England states, research was carried out to develop a proper mix design system for low volume roads from the standpoint of durability properties and then, once a good mix design system was available, check it to determine if it meets required strength properties. For low volume roads the performance is primarily affected by the environment and not by traffic, the approach in this study has been to determine the optimum value of a key volumetric property and an optimum number of design gyrations for producing compacted HMA mixes with adequate resistance against aging/high stiffness related durability problems. Six mixes were obtained in which only one can be characterized as a fine mix, and the remaining five were all relatively close to the maximum density line - three of them were with 9.5 mm Nominal Maximum Aggregate Size (NMAS), and the other two were with 12.5 mm NMAS. Based on the results from performance testing, film thickness of 11 microns in samples compacted to 7 percent voids was found to be desirable from considerations of stability and durability and a design VMA of 16 percent was determined to be optimum for producing durable and stable mixes for low volume roads. Results from testing of in-place mixes from good performing 10 to 12 year old low volume roads indicated a design gyration of 50 for obtaining a void content of 4 percent for mixes with gradations close to the maximum density line.

O uso de asfaltos modificados com polímeros tem crescido significativamente nas últimas décadas em função do aumento da densidade de tráfego, da carga por eixo nos veículos e da pressão dos pneus. Estes ligantes proporcionam o aumento a vida útil e a redução do custo de manutenção das rodovias. Os polímeros mais utilizados na modificação de asfalto são os copolímeros em bloco de estireno-butadienoestireno. Esta tese avaliou os efeitos de diferentes agentes compatibilizantes (óleos) e agentes de ligação no comportamento reológico de misturas asfálticas modificadas com copolímeros de estireno-butadieno-estireno, bem como a influência da sua estrutura, se linear ou radial. Para isto foram realizados análises convencionais e testes em reômetro de cisalhamento dinâmico. Os dados obtidos permitiram evidenciar a eficácia do óleo de xisto como agente compatibilizante, proporcionando excelente dispersão do polímero na matriz asfáltica e estabilidade a estocagem a altas temperaturas. Este óleo apresenta-se como uma opção tecnicamente viável para o óleo aromático atualmente em uso no mercado. Foi também verificado que o uso de enxofre como agente de ligação tem um efeito altamente positivo nas propriedades do ligante modificado, com significativa redução da tan ō, da deformação após aplicação de cargas cíclicas e elevação do módulo complexo, o que contribui para obtenção de pavimentos com maior resistência a deformação e ao trincamento por fadiga. / The use of polymer modified asphalts has grown significantly in the last decades due to the increase in traffic density, axle loading in vehicles and tyre pressure. These binders favor the increase of pavement life and the reduction of its maintenancement costs. The most used polymer for asphalt modification is styrene-butadiene-styrene blocked copolymers. This thesis evaluated the effects of different compatibilizers and crosslinkers on rheological behavior of styrene-butadiene-styrene copolymer modified asphalt binders, as well as the influence of its structure, linear or radial. Binder’s characteristics were determined by conventional analysis and tests in dinamic shear rheometer. Data obtained provided evidence of the positive effect of sulfur as crosslinker in modified binders properties, with high tan ō reduction, complex modulus increase and deformation reduction after application of cyclic loads, characteristics that turn possible the existence of pavements with greater rutting and fatigue resistance. It was also verified the shale oil efficacy as a compatibilizer agent, providing an excellent polymer dispersion inside asphalt matrix and a stable storage binder at high temperatures. This oil can be considered as a technical available option to aromatic oil presently in use at pavement industry.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A pavimentaÃÃo utiliza grandes volumes de recursos naturais requerendo aÃÃes que mitiguem os consequentes danos ambientais. Observando-se uma obra rodoviÃria, pode-se destacar aspectos que afetam o meio ambiente, como: desmatamento, extrativismo mineral para a produÃÃo de agregados e extraÃÃo e refino de petrÃleo para utilizaÃÃo em camadas asfÃlticas. Esta atividade faz uso ainda de processos que geram grandes volumes de passivos ambientais, tais como: fresagem e demoliÃÃes. O material fresado pode ser reciclado e reaproveitado, por exemplo, na produÃÃo de Misturas AsfÃlticas Recicladas a Quente (MARQs). As altas temperaturas que as misturas asfÃlticas exigem para tornarem-se trabalhÃveis submetem o ambiente a sua volta, especialmente os operÃrios que trabalham na produÃÃo do revestimento asfÃltico na usina, à condiÃÃes insalubres. Tendo em vista que o Cimento AsfÃltico de PetrÃleo (CAP), quando submetido a altas temperaturas, libera fumos que sÃo sabidamente nocivos. Para mitigar estes malefÃcios, pode-se utilizar as Misturas AsfÃlticas Mornas (MAMs).Essas misturas requerem temperaturas mais baixas do que as temperaturas normalmente empregadas na produÃÃo de Concretos AsfÃlticos (CAs).à possÃvel, ainda,combinar as duas tÃcnicas (MARQs e MAMs) utilizando as Misturas AsfÃlticas Recicladas Mornas (MARM).O presente trabalho tem como objetivo principal avaliar MARMs no que diz respeito a trabalhabilidade, a compactabilidade e ao comportamento mecÃnico das mesmas. Para isso, foram dosadas e caracterizadas em laboratÃrio 14 misturas do tipo CA, quais sejam: (i) duas misturas de referÃncia (uma dosada atravÃs da metodologia de dosagem Marshall e outra atravÃs da metodologia Superpave), (ii) trÃs MAMs (dosadas atravÃs da metodologia de dosagem Marshall) com, respectivamente, 20, 30 e 40ÂC de diminuiÃÃo das temperaturas utilizadas em todas as etapas do processo de dosagem, (iii) trÃs MAMs (dosadas atravÃs da metodologia de dosagem Superpave) com as mesmas diminuiÃÃes nas temperaturas jà mencionadas, (iv) trÃs MARQs (dosadas atravÃs da metodologia de dosagem Superpave) com 15, 35 e 50% de fresado em suas composiÃÃes e (v) trÃs MARMs com os mesmos percentuais de fresado utilizados nas MARQs e com a diminiÃÃo de temperatura de 40ÂC em todas as fases do processo. AlÃm das 14 misturas aqui descritas que foram avaliadas na fase de laboratÃrio do presente trabalho, foram dosadas outras quatro misturas em laboratÃrio para serem testadas em campo com a construÃÃo de trechos experimentais.Analisando-se os resultados encontrados percebe-se que as MARMs tem um potencial promissor, tendo em vista que as mesmas apresentaram parÃmetros volumÃtricos encontrados durante o processo de dosagem e comportamento mecÃnico similares se comparados aqueles obtidos para as misturas asfÃlticas convencionais. Tais parÃmetros foram alcanÃados sem a necessidade de mudanÃas nos equipamentos utilizados para a produÃÃo dessas misturas. Foi possÃvel atingir patamares de economia no consumo de CAP virgem de atà 45% e de agregados convencionais virgens de atà 50%, alÃm de uma possÃvel diminuiÃÃo do consumo energÃtico durante o processo de produÃÃo dessas misturas asfÃlticas devido a reduÃÃo das temperaturas em atà 40ÂC. / The paving process uses large amounts of natural resources thus requiring actions to mitigate the resulting environmental damage. Observing a road section, you can highlight activities that affect the environment, such as deforestation, mineral extraction for the production of aggregates and petroleum extraction and refining for use in asphalt layers. This activity also uses processes that generate large volumes of environmental liabilities, such as milling and demolition material. The reclaimed asphalt pavement (RAP) can be recycled and reused, for example in the production of RAP hot mixtures asphalts (HMA). The high temperatures that need to be used to produce acceptable workability of the asphalt mixtures can affect the environment and the workers on the construction site. The asphalt binder when subjected to high temperatures releases fumes known to be health hazardous. To mitigate these hazards, one can use the warm mixtures asphalt (WMA). This technology uses lower temperatures than the ones normally applied for HMA, thereby aforementioned emissions can be mitigated. It is also possible that the asphalt mixtures can be implemented with lower energy consumption. One can still use RAP WMA making use of both solutions already mentioned, RAP HMA and WMA. This work aims to use both techniques together and evaluate RAP WMA with respect to its workability, compactability and mechanical behavior. In order to achieve this objective it will be characterized in the laboratory HMAs with different RAP percentages and WMA additive. Such mixtures are also subsequently tested in the field using experimental sections. Analyzing the results it is noticed that the RAP WMAs has a promising potential since they presented the same volumetric parameters and mechanical behavior when compared to those obtained for the conventional asphalt mixtures. These parameters have been achieved without the need for changes in the equipment used for the production of these mixtures. It was possible to attain savings in binder consumption of up to 45% and conventional aggregates of up to 50%.A reduction in energy consumption is also achieved during the production of asphalt mixtures due to reductions in temperature to 40ÂC.

To evaluate the performance of Warm Mixture Asphalt (WMA) with varying amounts of recycled asphalt pavement (RAP) in comparison with Hot Mix Asphalt (HMA), comprehensive laboratory and field evaluations were conducted. Mix designs were performed for both WMA with a LEADCAP additive and HMA with large amounts of fractionated RAP materials. Hamburg Wheel Tracking (HWT) test was performed to evaluate the rutting and moisture susceptibility of both HMA and WMA laboratory mixtures. HMA mixtures with up to 50% RAP materials by binder replacement exhibited a better performance than WMA mixtures. However, when RAP materials were increased to 75% both WMA and HMA mixtures showed a superior performance. When a specially designed LEADCAP additive for a mixture with a high RAP content called "RAPCAP" was used, the performance was significantly improved. The existing Asphalt Bond Strength (ABS) test (AASHTO TP91-11) was modified to better evaluate the adhesion bond between asphalt binder and aggregate surface. Based on the modified ABS test results, it was found that the asphalt binder type significantly influenced the adhesion bond. To evaluate the performance of WMA mixtures in the field, test sections were constructed in Iowa, Minnesota and Ohio. The test sections were successfully constructed with less compaction effort than HMA and met the required field densities per each DOT's specification. All HMA and WMA mixtures collected from the test sections passed the HWT and the modified Lottman tests, which indicates high resistance to rutting and moisture damage. The asphalt binders were then extracted and recovered from the field samples then re-graded following AASHTO M320 and AASHTO MP19-10. The recovered asphalt binder grades were found to be higher than the target grades due to the existence of RAP materials in the mixtures except for asphalt binders extracted from WMA mixtures produced using "RAPCAP" additive.